Well this is the next logical question to the rotation one.
There are to different discussions about this...
1- To go fast with the least resistance and assuming that the water comes off the transom with a slight parting angle than you want to have the toe 'in'.
2- Handling, like the skis on your sled toe in and out effect the stability. So, in opposition to the theory of toe-in is faster, the toe-out is easier to steer in a walk. If your boat does not fly high enough to walk then its not an issue.
But none of this matters because you will try a little "in and out" after you deside on rotation which you also tried both ways.